The combo kit of MERV8 pre-filter and carbon filter is suitable for the HERO HS300 whole-house filtration system.The pre-filter will collect up to 90% particles between 3-10 microns in size such as pollen, dust, lint, dust mites, pet danger. The carbon filter will arrest household odors like cooking oil and smoke.With normal usage, it is recommended that you change this filter every 3-6 months.The kit includes 1 replacement MERV8 / Carbon combo filter.